1. Field of the Invention
The invention relates to a print control apparatus for outputting image data.
2. Related Background Art
Hitherto, it has been the practice that compressed image data is decompressed and is temporarily stored into a memory, and the data in the memory is again read out and is outputted as video data to a recorder.
In the above-mentioned prior art, however, since decompressed bit map image data is stored into the memory, there is a drawback in that the use frequency of the data bus increases.
It is, therefore, an object of the invention to provide a print control apparatus which can print and output bit map image data while executing a decompressing process without storing the bit map image data which was byte run length compressed into a memory.
Another object of the invention is to provide a print control apparatus in which, in accordance with a kind of data included in print data, the data can be directly outputted to a recorder without storing into a frame buffer or the data can be stored into the frame buffer and then outputted.
For the purpose of accomplishing the above objects, according to the invention, FIFO register is provided as a data buffer between a memory and a decompressor circuit and a cycle time for input/output is set so that a cycle time for writing is equal to or faster than a cycle time for reading.
A capacity of the buffer is equal to or larger than the product of the worst value of data compression and an amount of parallel data which is given to a video output per once, so that the compressed data is decompressed by the decompressor circuit without interrupting video data to be printed and outputted, thereby forming bit map image data.
In the print control apparatus for receiving print data, outputting it to a recorder, and printing, when compression image data exists in one band, the data is not stored in the frame buffer but is directly outputted to the recorder and, when a plurality of sets of, image data or other data exists in one band, the data is stored into the frame buffer and is outputted.